Two essentials of doctrine of separation of powers are division of powers and checks and balance. Control power including the work of oversight the government and officials and protecting human rights mainly checks and balances administrative power. The control system in the western world was born from Parliamentary Ombudsman of Sweden in 1809. After developing in two hundred years, by 2004, the ombudsman office, at the national level of government, exists in approximately 120 countries, which develops swiftly to the world and becomes the fashion of this time especially from 1980. The aim of this study is to discuss advanced the situations and characteristics of the countries in the world now by analyzing the types and functions of control systems in the world, and the roles, meanings, approaches, developments, selections, and primary powers of Ombudsman from international comparative points.